A systematic approach to explore the effects of dynamic interaction of liquid and solid phases on sediment-laden turbulent open channel flows is proposed. The investigation is carried out based on systematic analysis of basic momentum and continuity equations. The effect of suspended sediment on the turbulent flow is taken as a perturbation to an equivalent turbulent clear water flow of the same water depth. A perturbation analysis is then developed, in an attempt to quantitatively describe the physical process of the interaction between the turbulent flow and the suspended sediment. As a result, a generalized suspended sediment concentration distribution is derived directly from the momentum equation. After conducting an analysis of the generation of the induced Reynolds stress, the mean velocity profile of the perturbed flow is also obtained. The derived concentration and mean velocity distributions agree well with experimental data. The present analysis improves our understanding of the coupling mechanism, develops a framework, and offers new analytical results for further study. ¿ American Geophysical Union 1995